Add tests for jsdoccomments.

tests/cases/fourslash/fourslash.ts

@@ -448,6 +448,10 @@ module FourSlashInterface {
             FourSlash.currentTestState.verifyQuickInfoDisplayParts(kind, kindModifiers, textSpan, displayParts, documentation);
         }
 
+        public getSyntacticDiagnostics(expected: string) {
+            FourSlash.currentTestState.getSyntacticDiagnostics(expected);
+        }
+
         public getSemanticDiagnostics(expected: string) {
             FourSlash.currentTestState.getSemanticDiagnostics(expected);
         }

tests/cases/fourslash/getJavaScriptSemanticDiagnostics22.ts

@@ -0,0 +1,7 @@
+/// <reference path="fourslash.ts" />
+
+// @allowNonTsExtensions: true
+// @Filename: a.js
+//// function foo(...a) {}
+
+verify.getSemanticDiagnostics(`[]`);

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics1.ts

@@ -0,0 +1,19 @@
+/// <reference path="fourslash.ts" />
+
+// @allowNonTsExtensions: true
+// @Filename: a.js
+//// /**
+////  * @type {number}
+////  * @type {string}
+////  */
+////  var v;
+
+verify.getSyntacticDiagnostics(`[
+  {
+    "message": "\'type\' tag already specified.",
+    "start": 26,
+    "length": 4,
+    "category": "error",
+    "code": 1219
+  }
+]`);